It's called a maple, and in some of these renders, a silver maple leaf was used. But any other leaf type could be used, as long as it has a transparency map to go with it (silver maple leaf and corresponding transparency map are included here). There are 7 trunk meshes, each are named and uv-mapped ready for the textures. Each leaf is a welded set of 2 triangles, and is ready for the leaf texture/transparency map (they have been joined into 7 groups of leaves (~ 65000 vertices in each set), for a total of 115319 leaves. Just assign the leaf map to the 7 meshes.
There are 21 different leaf maps included: maples, oaks, others. Experiment with different maps and lighting conditions in the rendered scene to acheive the desired look. The smaller branches were just given a gray diffuse color.